Seme  Chemical  Relations   of 
Line-Sulphur  Solutions, 
Lead  Arson ate   and  Nicotine 

c,c. 


3    fiMM    53ft 


ENTOMOLOGY 
LIBRARY 


Some    Chemical   Relations   of   Lime- 
Sulphur  Solutions,  Lead  Arsen'ate 
and  Nicotine 


THESIS 


PRESENTED  TO  THE  FACULTY  OF  THE 
GRADUATE  SCHOOL 

OF 
CORNELL  UNIVERSITY 

FOR  THE 
DEGREE  OF  DOCTOR  OF  PHILOSOPHY 

BY 

CHARLES  CLEVELAND  HEDGES 
1912 


Some    Chemical    Relations    of   Lime- 
Sulphur  Solutions,  Lead  Arsenate 
and  Nicotine 


THESIS 


PRESENTED  TO  THE  FACULTY  OF  THE 
GRADUATE  SCHOOL 

OF 
CORNELL  UNIVERSITY 

FOR  THE 
DEGREE  OF  DOCTOR  OF  PHILOSOPHY 

BY 
CHARLES  CLEVELAND  HEDGES 

1912 


I 


INTRODUCTION 

The  introduction  of  lime-sulphur  spray  compound  into  New  York  State 
about  the  year  of  1907  and  1908  caused  a  great  many  inquiries  as  to  their  var- 
iation, and  value  of  it  as  a  repression  of  blister-mite  and  San  Jose  scale.  How- 
ever, apparently  slight  changes  in  material  used  or  in  methods,  have  resulted 
in  compounds  widely  different  in  appearance;  spraying  qualities,  and  insect- 
icidal  value  or  effect.  The  uncertain tity  of  securing  the  best  results  with  the 
home  made  mixtures,  due  to  their  vaiiiticn,  and  the  unpleasant  features  con- 
nected with  the  making  of  it  at  home  caused  many  to  welcome  the  advent  of 
the  commercial  preparations  in  concentrated  form.  The  number  of  brands 
grew  very  rapidly  due  to  the  marked  success  of  the  first,  when  in  1909  there 
were  at  least  five  on  the  market.  The  comparison  of  the  different  strengths  of 
the  several  brands,  led  to  the  investigation  as  to  their  comparative  value. 

So  with  the  advent  and  marked  success  of  the  Lime-sulphur  preparation, 
as  a  spraying  material,  for  the  control  of  the  blistor-mite  and  San  Jose  scale 
the  question  of  combining  materials  as  the  Arsenate  of  Lead  and  Nic- 
otine preparations,  naturally  came  to  be  considered  essential,  as  a  saver  of  time 
and  expense. 

At  the  suggestion  of  Professor  Cavanaugh,  of  the  Chemistry  Department, 
and  Professor  Crosby,  of  the  Entomological  Department,  a  chemical  study  of 
the  reactions  with  reference  to  the  advisiabilty  of  mixing  Lime-sulphur  solu- 
tion, Lead  Arsenate,  and  Nicotine  preparations  together  for  the  control  of  San 
Jose  scale,  Red  Bugs,  etc.,  by  one  spraying,  was  begun,  with  the  results  as 
given  in  this  paper. 

HISTORICAL 

CHEMICAL  BASIS  OF  LIME-SULPHUR  PREPARATIONS 

The  insecticidal  value  of  these  lime-sulphur  washes  rests,  not  in  any 
mechanical  mixture  of  the  t»vo  but  to  the  chemical  compounds  formed  by  the 
union  of  lime  or  rather  calcium  and  sulphur.  In  what  particular  manner  the 
lime  sulphur  solution  acts  as  an  insecticide  and  fungicide,  no  one  has  yet  clearly 
demonstrated.  What  specific  compounds  are  directly  responsible  for  the  eff- 
ects produced  we  are  not  yet  certain.  If  we  mix  together  the  two  elements  in 
a  dry  form  namely,  calcium  in  the  form  of  lime  (CaO)  and  sulphur  they  would 
not  combine  and  would  have  no  effect  on  each  other,  but  when  brought 
together  in  a  boiling  water  solution  for  about  forty-five  minutes  to  one  hour, 
they  combine  to  not  only  form  one  compound  but  a  series  of  compounds 
called  calcium  polysulphides  (CaSx). 

At  least  two  of  these  compounds  are  very  soluble  in  water  and  are  very 
destructive  to  insect  life  with  which  they  are  brought  in  contact.  There  may 
be  formed  at  least  five  compounds  of  calcium  and  sulphur;  since  one  part  of 
calcium  may  combine  with  four-fifths  its  weight  of  sulphur,  or  with  two- 
three,  four  or  five  times  that  amount.  The  different  calcium  sulphides  in  the 


lime-sulphur  are  not  very  readily  separable;  so  }he  exact  ir-secticidal  value  cf 
each  has  not  been  carefully  determined  but  it  has  been  generally  assumed 
tnat  the  two  highest  sulphides  are  the  most  erncient;  and  of  these  two  the  one 
higher  in  sulphur,  the  pentasulphide  (CaSs  )  is  supposed  to  be  of  a  higher  in- 
secticidal  value.  In  freshly  prepared  solutions  only  two  of  these  compounds 
are  present,  the  four  sulphur  compound  or  calcium  tetrasulphide  (CaS4  )  and 
the  five  sulphur  compound  or  calcium  pentasulphide  (  CaSs  ).  Calcium 
pentasulphide  contains  20  per  cent  of  calcium  and  80  per  cent  of  sulphur, 
which  is  at  the  rate  of  four  parts  of  sulphur  by  weight  for  one  part  of  calcium. 
Calcium  tetrasulphide  contains  24  per  cent  of  calcium  and  76  per  cent  of  sul- 
phur, which  is  at  the  rale  of  3.2  parts  of  sulphur  by  weight  for  one  part  of 
calcium.  Calcium  tetrasulphide  and  pentasulphide  produce  the  orange-red 
color  in  the  solution.  In  the  chemical  changes  that  take  place  between  lime 
and  sulphur  when  they  are  heated  in  waler,  another  compound  is  unavoidably 
formed,  but  in  smaller  amounts;  this  is  a  chemical  compound  of  three  elements 
calcium,  sulphur  and  oxygen.  This  calcium  thiosulphate  (CaSz  O$  )  which 
is  easily  soluble  in  water  and  is  therefore  contained  in  the  solution  along  with 
the  sulphides  of  calcium.  The  value  of  this  compound  for  spraying  purposes 
is  not  known  but  on  exposure  to  air  it  is  changed  by  oxidation  to  calcium  sul- 
phite (CaSO3  )  and  free  sulphur.  Calcium  sulphite  is  insoluble  in  water  and 
therefore  appears  in  the  sediment  or  in  the  undissolved  portion  of  lime-sulphur 
preparations,  usually  forming  the  chief  part  of  the  sediment.  The  free  sul- 
phur formed  by  the  decomposition  of  thio-sulphate  recombines  with  calcium 
and  goes  into  solution  in  the  operation  of  making  lime-sulphur  solution,  when 
enough  lime  is  present.  The  sulphite  may  later  take  up  more  oxygen  and 
form  calcium  sulphate  (  CaSO4  )  an  insoluble  part  of  the  sediment.  The  de- 
sirable chemical  changes  are  the  formation  of  the  soluble  lime-sulphur  com- 
binations, the  calcium  tetrasulphide  and  the  calcium  pentasulphide  and  perhaps 
the  formation  of  the  calcium  thio-sulphate;  the  indersirable  reactions  are  the 
oxidizing  of  the  thio-sulphate,  after  the  mixture  cools,  with  the  formation  of 
sulphates  and  sulphites  (1). 

EFFICIENCY  OF  LIME-SULPHUR  IN  RELATION  TO  CHEMICAL 
COMPOSITION 

Dr.  L.  L.  VanSlyke  in  Bulletin  No.  329,  of  the  New  York  State  Experiment 
Station  at  Geneva,  states  "that  it  is  held,  as  the  results  of  some  experimental 
work  that  the  effect  of  the  lime  sulphur  mixture  is  not  due  to  the  direct  ac- 
tion of  calcium  penta-sulphide  (CaSs  )  or  calcium  tetra-sulphide  (CaS4  )  but  is 
due  rather  to  compounds  that  are  formed  from  those,  either  calcium  thio-sul- 
phate (CaS2O3  )  or  free  sulphur  or  both. 

If  the  direct  effective  substance  is  calcium  thiosulphate,  then  the  amount 
that  can  be  formed  from  the  lime-sulphur  solution  is  directly  dependent  upon 
and  proportional  to  the  amount  of  calcium  pentasulphide  or  calcium  tetrasul- 
phide in  solution. 

(1)     Bui.  No.319  and  No.  320  New  York  Experiment  Station  (Geneva) 

272678 


(|>f  the  sulphur  set  free  from  the  pentasulphide,  tetrasulphide  and  thio- 
sulphate  is  the  effective  agent,  then  the  amount  of  compounds  in  solution  cap- 
able of  furnishing  the  largest  amount  of  free  sulphur  directly  determines  the 
value  of  the  solution.  Calcium  pentasulphide  is  capable  of  furnishing  more 
free  sulphur  by  decomposition  than  the  tetrasulphide  and  this  more  than  the 
thiosulphate. 

If  the  free  sulphur  is  the  material  desired  then  the  solution  containing  the 
largest  amount  of  pentasulphide  is  the  most  valuable.  It  is  now  commonly 
believed,  whether  correct  or  not,  that  the  solution  containing  the  most  penta- 
sulphide is  the  most  effective,  at  least  in  connection  with  the  destruction  of 
scale  insects.  What  ever  may  prove  to  be  the  facts  in  relation  to  the  manner  of  ac- 
tion of  the  lime-suphur  solution,  it  is  obvious  that  its  efficiency  stands  close 
and  direct  relation  to  the  amount  of  sulphide  compounds  contained  it  it,  or,  in 
other  words,  to  the  chemical  composition  of  the  solution." 

The  difference  in  concentration  and  amount  of  Calcium  thio-sulphate 
(CaS2O3)  present  in  home-made  solutions,  compared  with  the  more  concen- 
trated form  prepared  by  manufacturers  are  caused  by  the  manufacture  in  pre- 
paring a  more  concentrated  solution,  by  evaporation,  changes  some  of  the  cal- 
cium thio-sulphate  to  calcium  sulphite  leaving  a  smaller  percentage  of  calcium 
thiosulphite  in  solution  than  in  the  home-made  preparations.  The  calcium 
sulphite,  as  formed  under  the  conditions  stated  is  found  in  the  sediment  as 
such  or  oxidized  to  Calcium  sulphate  (CaSO4)  which  is  insoluble  and  in  either 
form  is  a  loss  to  the  manufacturer,  and  the  consumers. 

ARSENATE  OF  LEAD 

This  substance  was  first  prepared  as  an  insecticide  by  Mr.  F.  C.  Moulton 
in  1892,  while  acting  as  chemist  in  Maiden,  under  Mr.  E.  H,  Forbush,  Field 
Director,  in  charge  of  the  work  of  destroying  the  gypsy  moth. 

In  the  work  of  destroying  the  gypsy  moth  it  was  soon  discovered  that  Paris 
green  would  not  kill  many  of  the  catterpillars,  even  when  used  in  as  large  a 
proportion  in  water  as  was  possible  without  injury  to  the  foliage  of  the  trees. 
It  therefore  seemed  necessary,  to  discover,  if  possible,  some  insecticide  that 
would  destroy  the  caterpillar  and  at  the  same  time  not  injure  the  most  delicate 
foliage. 

The  first  public  mention  of  arsenate  of  lead  was  in  the  report  of  the 
Massachusetts  Agricultural  College,  October,  1893,  page  23. 

The  name  "gypsino"  was  given  to  this  insecticide  by  Mr.  Moulton,  but  as 
there  was  an  entirely  different  product  on  the  market  by  the  same  name,  this 
insecticide  was  called  arsenate  of  lead. 

CHEMICAL  COMPOSITION 

The  arsenate  of  lead  used  in  spraying,  operations,  to  be  exact,  is  not  a  salt 
whose  composition  may  be  expressed  by  a  single  formula,  but  instead  is  a 
mixture  of  both  diplumbic  and  tri-plumbic  arsenates,  the  relative  quantities  of 
each  depending  principally  upon  the  source  of  the  soluble  lead  salt  used  in 
making  it. 


In  the  preparation  of  the  arsenate  of  lead  it  is  only  necessary  to  form  a 
chemical  union  between  the  common  lead  oxide  (litharge),  PbO,  and  arsenic 
pentoxide,  (As2Os),  but  in  order  to  obtain  a  product  suitable  for  use  as  an 
insecticide,  the  chemcial  union  must  take  place  between  soluble  salts  contain- 
ing these  oxides.  In  general  practice,  arsenate  of  lead  suitable  for  spraying 
purposes  is  prepared  by  bringing  together  commercial  grades  of  acetate  or 
nitrate  of  lead  and  arsenate  of  soda.  Owing  to  the  variable  composition  of 
these  commercial  salts,  a  chemical  analysis  is  indespensible,  as  indicating  the 
relative  amounts  to  be  used.  All  such  calculations  must  be  based  on  the 
quantity  of  lead  oxide  (PbO)  found  in  the  lead  salt  and  that  of  arsenic  pen- 
toxide (As2  O5  )  contained  in  the  arsenate  of  soda,  making  due  allowance  for 
the  other  acidulous  radicals  which  may  precipitate  the  lead. 

Where  the  acetate  of  lead  is  used  approximately  the  whole  of  the  arsenate 
of  lead  product  consists  of  tri-plumbic  arsenate,  as  indicated  in  the  following 
equation. 

3Pb(C2  H3  O2  )  2;  3H2  O+2Na2  H  AsO4    (H2O)n- 
Pb3  (AsO4)2   +  4NaC2H3O2  +  2C2  H4  O  2  +  nHzO. 

The  following  equation  represents  the  reaction  between  arsenate  of  soda    and 
nitrate  of  lead  by  Smith:--(l) 

5Pb  (No  3  )2  +4N  a  2  HAs04  (H  2  0)n  = 

Pb3(AsO4  )2  +  2PbHAsO4  +  8NaNO3  +  2HNO3  +  n  (H2  O). 

EFFICIENCY  AS  A  SPRAYING  MATERIAL. 

Arsenate  of  lead  remains  in  suspension  in  water  much  longer  than  Paris 
green,  because  of  its  very  low  specific  gravity,  which  is  1,00688  while  that  of 
Paris  green  is  3,42225.  In  spraying,  the  low  specific  gravity  of  arsenate  of  lead 
and  its  consequent  suspension  in  water  for  a  considerable  length  of  time  make 
it  possible  to  distribute  it  more  evenly  over  vegetation.  The  white  color  is  also 
a  decided  advantage,  for  one  is  enabled  to  see  at  a  glance  whether  a  tree  or 
shrub  has  been  sprayed;  and  it  is  a  noteworthy  fact  that  this  insecticide  adheres 
to  foliage  for  longer  than  any  similar  substance  now  in  use.  It  is  undoubtedly 
true  that  larger  proportions  of  arsenate  of  lead  must  be  used  than  of  Paris 
green  but  this  can  be  done  with  entire  safety  to  the  vegetation.  The  cost  of 
the  insecticide  forms  a  very  small  part  of  the  cost  of  spraying;  and  since  arsen- 
ate of  lead  remains  on  the  foliage  so  much  longer  than  other  insecticides,  a 
much  larger  proportion  can  be  used  and  even  then  be  much  cheaper  than 
substances  which  wash  off  readily  in  showers,  making  it  necessary  to  spray 
the  trees  the  second  time. 

A  large  percentage  of  the  spraying  at  the  present  time  is  with  a  mixture 
of  an  insecticide  and  a  fungicide;  because  as  has  already  been  said,  the  great 
expense  is  in  the  labor,  and  not  in  the  materials  used;  and  when  the  insecticide 
and  fungicide  can  be  applied  together,  the  cost  of  one  spraying  is  saved.  Ar- 

(1)  Annual  Report  State  Board  of  Agriculture,  1897,  page  354. 


senate  of    lead  can  be  mixed  with  Bordeaux   mixture,    very    successfully,    just 
the  same  as  Paris  green. 

The  investigation  concerning  the  mixing  Lime-sulphur  with  Arenate 
of  Lead  was  published  by  C.  E.  Bradley  and  H.  V,  Tartar  (1)  with  the 
following  results  in  connection  with  further  studies  of  the  reaction  of  Lime- 
sulphur  solution  and  alkali  waters  on  Lead  Arsenate.  Haedden  has  stated  (2) 
that  Lead  Arsenate  is  more  soluble  in  water  containing  alkali  salts  than  in 
mineral  waters. 

TABLE  I. 

Composition  of  the  Lime-sulphur  Solution  before  and  after  addition  of 
Lead  Arsenate. 

Grams  per  1 0OOcc.  Filtrate       Filtrate  from  neut- 
Blank  from    acid    arsenate    and  ral  Arsenate 

Lime-sulphur  Lime-sulphur  Lime-sulphur 

Total  Sulphur      10.750  10.256  

"     CaO  4.380  4.060  

"     As2O5  .095  .012 

Above  results  indicate  that  8  times  as  much  arsenate  is  rendered  soluble 
from  the  acid  arsenate  as  from  the  neutral,  or  calculated  from  original  material 
this  would  be  equivalent  to  0.25  percent,  of  saluble  As2  O$  from  neutral  1.98 
percent.  As2  Os  from  acid  Lead  Arsenate.  Distinct  losses  of  sulphur  and  lime 
have  also  taken  place  in  the  acid  arsenate  mixture  and  it  is  evident  that  there 
is  a  mutual  decomposition  when  acid  lead  arsonate  is  mixed  with  the  lime 
sulphur  solution. 

TABLE  II. 
Analysis  of  the  residue  from  the  Mixture  of  Lime-Sulphur  and  Lead  Arsenate. 

Neutral  Lead  Arsenafe  Acid  Lead  Arsenate 

residue  residue 

Percent.  Percent. 

Free  Sulphur  0.70  20.80 

PbS  1.47  14.80 

CaO  10.40 

The  reactions  and  loss  of  sulphur  and  lime  from  solution,  as  shown 
above  are  much  more  pronounced  with  the  acid  than  with  neutral  arsenate 
and  it  is  therefore  advisable  to  employ  the  neutral  form  when  desiring  to  com- 
bine lime-sulphur  and  lead  arsenate.  Waters  containing  considerable  quan- 
tities of  alkali  carbonates  should  be  avoided  in  mixing  lead  arsenate  for  spray- 
ing purposer,  as  their  tendency  is  to  render  the  arsenic  soluble  and  do  not 
dissolve  the  lead.  Soluble  arsenic  is  one  of  the  most  important  things  to  avoid 
as  in  most  cases  it  is  the  main  cause  for  the  injury  to  foliage. 

(1)  Journal  Industrial  Engineering  Chemistry,  Vol.  II,  No.  7,  p.  328,  (1910) 

(2)  Bulletin  131  Colorado  Experiment  Station. 


NICOTINE. 
Nicotine-  cxPyridyl-b-tetrahydro-n-methyl  pyrrol  (?) 

C|oH|4N2  =        ^N^ 

CH^       CH 

I  NX  CH3 

— '    XCH2 


, 

CH2    —    CH 


boiling  at  247°  ,  with  Specific  gravity  1.011(15°),  and  Laevocrotatory  occurs 
in  the  leaves  of  the  tobacco  plant,  Nicotiania  Tabacum,  in  quantities  varying 
from  0.6  to  8  per  cent,  depending  upon  the  varieties.  As  a  rule,  the  better 
qualities  of  tobacco  contain  less  nicotine  than  the  poorer  sorts. 

HISTORY. 

Posselt  and  Remian  "discovered  nicotine  (1828).  Since  1991  Blau,  but 
more  especiallo  Pinner,  has  studied  its  transposition  reactions,  the  constitu- 
tional formula  proposed  by  Pinner  harmonizes  with  its  deportment  and  has 
more  receetly  been  forfeited  by  the  experiments  of  Ame  Pictet  and  Cropioux 
(1895),  which  doubtless  led  to  the  synthesis  of  nicotine  by  Pictet  (C.  R.  1903, 
137,  810)  and  has  been  shown  to  be  pyridyl-N-methyl-pyrrohdine.  The 
method  of  synthesis  is  as  follows:-  Nicotine  acid  is  transformed  first  into  i  s 
ethylester,  and  then  into  the  amide;  this  bromine  and  alkali  (Hoffman's  re- 
action) gives  amino-pyridine  and  when  the  salt  of  this  base  with  mucic  acid 
is  distilled,  N-pyridyl-pyrrole. 

CH     :     CH 
N  ' 

^CH    :    CH2 


is  formed.     When  the  vapour  of    this    compound  is    passed  through  a  heated 
tube,  it  is  transformed  into  the  isomeric  a-pyridyl-pyrrole, 


CH    .    CH 
11  11 

— C  CH 


V 


This  forms  a  potaasic  derivative  which  with  methyliodide  yields 


CH    .    CH 
11  11 

CH 


CH3 


NCH3I 
and  this,  when  distilled  with  lime,  gives 

CH—      -  CH 


' 


N(CH3)    .     CH 

^-pyridyl-N  -methyl  pyrrol,  which  can  be  converted  into  ^-pyridyl-N-methyl 
pyrolidine  (i-nicotine)  by  the  addition  of  hydrogen.  The  racemic  alkaloid  thus 
obtained  may  be  resolved  into  its  optically  active  components  by  the  aid  of 
O^-tartaric  acid  when,  ]  -nicotine-d-tartrate  chrystallizes  out  first. 

OCCURENCE 

In  leaves  of  tobacco  (Nicotiana  Tabacum)  and  in  the  leaves  of  Macrophy|la 
rustica  and  N.  glutinusa.  Occurs  also  in  Pituri.  According  to  Zeise  and 
Vohl  and  Eulenberg  it  is  not  present  in  tobacco  smoke,  but  Heubel  obtained 
evidence  of  its  presence  therein. 

PREPARATION 

Tobacco  leaves  (10  parts)  are  soaked  in  water  24  hours,  and  the  mixture 
heated  to  100°  by  steam.  The  aqueous  extract  is  mixed  with  lime  (1  part) 
and  distilled.  The  distillate  is  neutralized  by  oxalic  acid  and  evaporated  to  a 
thin  syrup.  Addition  of  concentrated  KOH  now  separates  the  base,  which  is 
rectified  in  a  current  of  hydrogen. 

PROPERTIES 

Colorless  liquid,  not  frozen  at  -IQo  .  Smells  like  tobacco,  unless  it  is  quite 
pure.  It  is  very  hygroscopic.  Mixes  with  water,  developing  heat,  and  is  very 
soluble.  It  has  a  disagreeable  odor  and  burning  taste.  A  very  violent  poison. 
Leavorotatory.  Optical  activity  of  its  aqueous  solution  varies  greatly  with 
concentration  in  a  4  percent,  solution,  [d]  D  =  -77°  at  20°  :  in  a  .88  percent. 
solution  [d]  D  =  -79°.  Solutions  of  salts  of  nicotine  are  dextrorotatary.  Nic- 
otine turns  brown  on  exposure  to  air  and  light.  Its  solutions  are  strongly  al- 
kaline. Its  very  soluble  in  water,  alcohol,  ether,  terpenes  and  fatty  oils.  At 
100°  it  dissolves  10  percent,  of  sulphur,  but  on  cooling  it  separates  again 
Ether  extracts  it  from  aqueous  solutions.  KOH  separates  it  from  aqueous  so- 
lutions. 


ESTIMATION 

(I)  By  distilling  with  potash,  extracting  the  distilliation  with  ether,  evapo- 
rating the  ether,  converting  the  residue  into  sulphate  and  repeating  the  pro- 
cess. (2)  Tobacco  is  mixed  with  aqueous  NaOH  and  some  alcohol,  and  ex- 
tracted with  ether.  The  extract  is  evaporated  and  the  nicotine  distilled  over 
with  steam  and  estimated  by  titration  with  standard  acid,  or  by  the  polari- 
meter. 

EXPERIMENTAL. 

OUTLINE  OF  EXPERIMENTS. 

1.  Determination  of  Total  Sulphur  and  Lime    (CaO)    in    a    dilute    Lime- 
sulphur  solution  of  the  different  strengths  as  used  in  the  experiments. 

2.  Determination  of  the  amount  of  Nicotine,  sulphur  trioxide,  (SOs  )  and 
the  acidity  or  alkalinity  of  the  different  Nicotine  preparations  used,  as  Nicotine 
sulphate,  Black  Leaf  40,  and  Nico-fume. 

3.  Determination  of  the  soluble  Arsenic  oxide  (As2  O5  )  and  the    acidity 
of  the  arsenate  of  Lead  used. 

4.  Mixing  of  the  Lime-sulphur  of  the  different  dilutions  with  the  arsenate 
of  Lead  at  the  rate  of  four  pounds  of  the  Lead  arsenate  to   one    hundred    gal- 
lons of  the  solution,  and  determining  the  amount    of    total    suphur    and    Lime 
(CaO)  remaining  in  solution.     Also  filtering,  drying,    and    weighing    sediment. 
Using  both  acid  and  neutral  Lead  Arsenate. 

5.  Mixing  the  solutions  as  in  number  four  and  trying  the  effect  of  carbon 
dioxide  (CO2  ),  as  in  the  carbon  dioxide  spraying  apparatus,  on  the  increase  of 
the  soluble  Arsenic  Oxide  (As2  O$  )  and  the  solution  and  the    decrease  of  the 
efficiency  of  the  mixture. 

6.  Mixing  the  solutions  of  the  Lime-sulphur  and  arsenate  lead,  again,    as 
in  number  four  and  adding  2  cc  of  the  different  Nicotine  preparations    to    the 
mixture  and  making  to  a  dcfinate  volume  (1000    cc).     Then    determining    the 
amount  of  Total  Sulphur  and  Lime  (CaO)  remaining  in  solution.     Also  filtering, 
drying,  and  weighing  the  sediment. 

7.  Effect  of  carbon -dioxide  (CO2  )  as  in  spraying  apparatus  upon  a  dilute 
Nicotine  solution,  diluting  one  to  four  hundred. 

8.  Preparation  of  Nicotine  Sulphate  from  tobacco    stems    or    poor    grade 
tobacco. 

METHODS  OF  ANALYSIS 
DETERMINATION  OF  NICOTINE 

Solutions  required  are  (a)  Alcoholic  soda.-Dissolve  6  grams  of  sodium 
hydroxide  in  40  cc.  of  water  and  50  cc  of  90  per  cent,  alcohol,  (b)  Sodium 
hydroxide. -Dissolve  4  grams  of  sodium  hydroxide  in  1GOO  cc  of  water,  (c) 
Sulphric  Acid. -A  standard  solution. 

Weigh  out  from  5  to  6  grams  of  tobacco  extract  into  a  small  beaker.  Add 
10  cc  of  the  alcoholic  soda  solution  and  follow  with  enough  chemically  pure 
powdered  calcium  carbonate  to  form  a  moist  but  not  a  lumpy  mass.  Mix  the 


whole  thoroughly  and  transfer  to  a  Soxhlet  extractor  and  exhaust  for  about 
five  hours  with  ether.  Evaporate  the  ether  solution  at  a  low  temperure  by 
holding  over  the  steam  bath,  and  take  up  the  residue  with  50  cc  of  the  dilute 
sodium  hydroxide  solution.  Transfer  this  residue  by  means  of  water  to  a 
500  cc  Kjeldahl  flask,  and  distill  in  a  current  of  steam,  using  a  condenser. 
(Use  a  few  pieces  of  pumice,  and  a  small  piece  of  paraffin,  to  prevent  bump- 
ing and  frothing.)  Continue  the  distilliation  till  all  the  nicotine  has  passed  over 
the  distillate  usually  varying  from  400  to  500  cc.  When  the  distillation  is  com- 
plete, only  about  15  cc.  of  the  liquid  should  remain  in  the  distillation  flask. 
Titrate  the  distillate  with  standard  sulphuric  acid  using  cochnical  as  indicator. 
One  molecule  of  sulphuric  acid  solution  is  equivalent  to  two  molecules  of  nico- 
tine. This  is  the  Official  method  adopted  by  the  Official  Agricultural  Chemists. 

DETERMINATION  OF  TOTAL  SULPHUR 

Take  an  aliquot  portion  of  the  solution  representing  1  to  2  cc  of  the  orig- 
inal concentrated  Lime-Sulphur  solution,  place  in  a  200  cc.  beaker,  with  25  cc. 
of  hydrogen  peroxide  (H2  O2  ),  2  cc  of  concentrated  Sodium  hydroxide  and 
about  25  cc  of  water.  Then  the  beaker  after  being  covered  with  a  beaker 
cover  was  placed  on  the  water  bath  for  two  hours  until  all  of  the  sulphur  was 
oxidized  to  calcium  sulphate.  After  oxidation  is  complete,  neutralize  the 
solution  with  hydrochloric  acid,  precipitate  the  sulphur  with  Barium  Chloride 
solution  as  Barium  Sulphate.  Let  stand  over  night,  filter  and  weigh  the  pre- 
cipitate after  ignition,  in  a  platium  or  porcelain  crucible. 

DETERMINATION  OF  LIME  (CaO) 

Take  an  aliquot  portion  of  the  dilute  Lime-sulphur  solution  and  oxidize 
the  suphur  in  the  solution  with  hydrogen  peroxide,  as  in  the  determination  of 
Total  Sulphur;  make  the  solution  acid  with  acetic  acid,  then  alkaline  with  am- 
monium hydroxide  and  precipitate  the  calcium  as  calcium  oxalate.  Filter  the 
solution  while  hot,  wash  precipitate  thoroughly  and  place  the  filter  paper  con- 
taining the  precipitate  in  hot  water  containing  about  5  cc  of  concentrated  sul- 
phuric acid.  Titrate  the  solution  with  a  standard  Potassium  purmanganate  so- 
lution in  the  usual  manner. 

The  determination  of  Total  Arsenic  and  water  soluble  arsenic  was  deter- 
mined by  the  methods  outlined  in  the  Bulletin  No.  107  (revised)  of  the  Official 
Agricultural  Chemists,  Department  of  Agriculture,  Bureau  of  Chemistry,  so- 
lution used  in  the  experiment:- 

1.  Concentrated  Lime-sulphur  solution. 

Specific  Gravity  =  1 . 1 750  or  2 1  °   Baume'. 
Per  cent  Total  Sulphur  =  12.86 
Per  cent  Total  Lime  (CaO) =6.43 
Per  cent  Calcium  (Ca.)=-4.59 

2.  Nicotine  solution  called  Black  Leaf  40,  Nicotine  sulphate  or  Nico-sul. 

Specific  Gravity  of  solution  at  15°  C.=  1.2120. 

Per  cent  of  Nicotine  in  the  solution  ^40.50 

Per  cent  of  combined  Nicotine  (as  sulphate)—  13.12 

Acidity  expressed  as  H2  SO4  ~12. 13  percent. 

Came  the  same  using  Phonolthalein  or  Cochineal  as  Indicator. 


Total  Sulphur  in  2  cc  of  solutions  .1274  grams  or  5.25  percent 

Sulphur  in  solution  as  H£    SC>4    in    2    ccS  .C960    grams    or    3.96 

percent 

Sulphur  in  solution  combined  to   Nicotines  .03 1 4    grams    or    1.29 

percent 

Trace  of  Lime  in  the  solution. 

Some  of  the  Nicotine  in  the  solution  is  not  combined  as    sulphate 

although  there  was  an  excess  of  HZ  SO4    present.     The    Nicotine 

may  be  combined  in  some  way  with  the  organic    matter    present. 

Quite  a  little  organic  matter  is  present  in  this  solution. 

3.     Nicotine  solution  called  Nico-fume. 

Specific  Gravity  of  the  solution  at  15°  C.S  1.0139 

Per  cent  of  Nicotine  in  solutions  36.04 

Per  cent  of  Nicotine  combined  as  sulphate— 6. 1 5 

Total  sulphur  in  2  cc,  of  solutions  .0123  grams  or  .60  per  cent. 

Sulphur  in  solution  combined  to  Nicotines  .0123  grams. 

There  is  no  lime  present  in  the  solution. 

Solution  is  Alkaline. 

Alkalinity  (Phenolthaloin  as  ind.)  expressed  as  NaOHss  .24  p.  ct. 

Alkalinity    (Cochineal    as    Indicator)    expressed    as    NaOHsl.Ol 

percent 

The  increased  alkalinity  with  cochineal  as  indicator  may    be    due 

entirely  to  free  Nicotine  present.     Somtion  does  not  contain  hardly 

any  organic  matter,  and  is  not  very  thick. 

4.  Nicotine  solution  called  Rextract,  which  is  a  mixture  of    Nicotine    and 

Lime-sulphur  containing  some  sediment. 

Hydrogen  sulphide  is  given  off  of  the  solution  abundantly. 

Total  sulphur  in  2  cc.  of  the  solutions  .2822  grams. 

Total  Lime  (CaO)  in  2  cc.  of  the  solutions .  1 84 1    " 

Total  Calcium  in  2  cc.  of  the  solutions  .1315  grams 

Hard  to  obtain  a  uniform  sample  of  the  solution  and  sediment 

5.  Grasselli's  Arsenate  of  Lead-Paste,  and  Hemingway's  Lead  Arsenals 

Both  of  these  were  acid. 

(Grasselli's)  Acidity  expressed  as  H2  SO4  sO.31  percent. 

(Hemingway's)  sO.37  percent. 

6.  Solution  of  Hydrogen  Peroxide. 

Total  Sulphur  in  50  cc.  of  the  solutions  .0040  grams. 
Total  Lime  (CaO)  in  50  cc.  of  the  solutions  none 

Experiment  No.  1  was  to  determine  the  amount  of  sulphur  and  Calcium 
lost  from  the  Lime-sulphur  solution  by  mixing  2  cc  of  the  Nicotine  compound 
with  a  dilute  Lime -sulphur  of  the  dilution  1:10. 


TABLE  A. 


100  cc  of  the  Lime-sulphur  solution  was  diluted  to  1000  cc    by    the    addi- 
tion of  water  after  the  following  were  added: 


Per  lOOcc  of 
Solution 

Dilute  Lime 
sulphuritSol. 

2cc  Nico- 
fume 

2cc  Nico- 
sul  (acid) 

2cc  Nico-       2cc 
sul  (neut)  Rextract 

Grame  of 
Sediment 

trace 

trace 

trace 

trace 

trace 

Grams  of 
Total  S. 
Grams  of 
S.  lost 

2.0090 
0.0000 

1.8778 
0.1312 

1.8153 
0.1937 

1.8583 
0.1507 

1.7878 
0.2212 

Grams  of 
Lime 

0.7492 

0.7485 

0.7473 

0.7490 

0.7476 

Grams  of 
Lime  lost 

0.0000 

0.0007 

0.0019 

0.0002 

0.0016 

Grams  of 
Calcium 

0.5351 

0.5346 

0.5338 

0.5350 

0.5340 

Grams  of 
Ca.  lost 

0.0000 

0.0005 

0.0013 

0.0001 

0.001  1 

Percent 
loss  of 
Total  S. 

none 

6.53 

9.64 

7.50 

11.01 

Percent 
loss  of 
Calcium 

none 

0.09 

0.24 

0.00 

0.20 

The  result  in  experiment  number  one,  as  found  in  the  Table,  A  shows 
that  at  the  dilution  of  one  to  ten  a  very  small  percentage  of  calcium  is  thrown 
out  of  solution  by  mixing  any  of  the  Nicotine  compounds  with  Lime-sulphur 
solution  and  the  acid  Nicotine  thrown  out  almost  three  times  as  much  calcium 
out  of  solution  as  the  Nico-fume  which  is  alkaline,  and  twenty  four  times  as 
much  as  with  the  neutral  ''Nico-sul"  compound.  The  loss  of  calcium  in  any 
of  the  mixtures  are  not  large  and  hardly  to  be  considered.  As  to  the  sulphur 
there  is  more  than  three  percent  more  of  sulphur  thrown  out  of  the  solution 
by  the  use  of  acid  "Nico-sul"  compound  than  with  the  alkaline  solution  of 
Nico-fume  and  a  little  more  than  two  percent  more  sulphur  is  lost  by  the  use 
of  acid  "Nico-sul,,  compound  than  with  the  neutral  "Nico-sul"  solution.  The 
alkaline  "Nico-fume"  solution  throws  out  of  solution  more  calcium  than  the 
neutral  "Nico-sul"  solution  due  to  the  alkaline  substance  replacing  some  of  the 
lime.  With  the  sulphur  lost  it  is  just  the  opposite  as  the  lime-sulphur  solution 
is  alkaline  and  the  alkaline  "Nico-fume"  helps  to  hold  it  in  solution.  At  this 
dilution  the  results  show  that  it  is  best  to  use  neutral  or  slihtly  alkaline  Nico- 
tine and  not  the  acid  Nicotine  solutions,  as  acid  "Nico-sul"  compounds  with 
the  lime-sulphur  solutions.  The  use  of  Rextract  is  not  advisiable  as  it  is  a 
mixture  of  Lime-sulphur  solution  and  Nicotine  compound  and  contains  a  large 
quantity  of  hydrogen  sulphide,  besides  the  difficulty  of  obtaining  a  uniform 


sample  due  to  large  quantity  of  sediment  present  in  the  preparation. 

Experiment  No.  2  was  to  determine  the  amount  of  sulphur  and  Calcium 
lost  from  the  Lime-sulphur  solution  by  the  mixing  of  2  cc.  of  the  Nicotine  so- 
lution with  a  dilute  Lime-sulphur  solution  of  the  dilution  1:20. 

TABLE  B 

50  cc.  of  the  concentrated  Lime-snlphur  solution  was  diluted  to  1000  cc. 
by  the  addition  of  water  after  the  following  was  added. - 

PerlOOccof     Dilute  Lime-  2cc  Nico-         2cc  Nico-         2cc  Nico-         2cc 

Rolution         sulphur  Sol.  fume  sul  (acid)         sul  (neut)   Rextract 


Grams  of 
Sediment 

trace 

trace 

0.0290 

trace 

trace 

Grams  of 
Total  S. 

.8332 

.8040 

0.7929 

.7857 

.8166 

Grams  of 
S.  Lost 

.0000 

.0292 

0.0403 

.0475 

.0166 

Grams  of 
Lime 

.3760 

.3716 

0.3752 

.3760 

.3746 

Grams  of 
Lime  lost 

.0000 

.0044 

0.0008 

.0000 

.0014 

Grams  of 
Calcium 

.2686 

.2654 

0.2680 

.2686 

.2677 

Grams  of 
Ca.  lost 

.0000 

.0032 

0.0006 

.0000 

.0009 

Percsnt 
loss  of 
Total  S 

.0000 

3.50 

4.83 

5.70 

1.99 

Percent 
loss  of 
Calcium 

,0000 

1.19 

.22 

.00 

.33 

The  results  in  Experiment  number  two  found  in  Table  B.  shows  that  at 
the  dilution  of  one  to  twenty  a  very  small  quantity  of  Calcium  is  thrown  out  of 
solution  by  the  mixing,  just  the  same  as  in  number  one.  The  "Nico-fume" 
which  is  alkaline  throws  out  of  solution  1.19  percent  of  Calcium  due  to  the 
replacement  of  the  Lime  by  the  alkaline  substance,  while  the  neutral  "Nico- 
sul"  solution  causes  no  loss  of  Calcium  and  the  loss  due  to  the  acid  Nico-sul 
solution  was  .22  of  one  percent,  showing,  that  the  acid  Nico-Sul  in  the  more 
dilute  solution  had  not  as  detrimentral  effect.  As  to  the  sulphur  there  were 
1 .33  percent  more  sulphur  thrown  out  of  solution  by  the  acid  Nico-sul  solution 
than  with  the  alkaline  Nico-fume  solution  showing  approximately  the  same  re- 
sults as  shown  at  the  dilution  of  one  to  ten.  In  the  more  dilute  solution  of  one 
to  twenty  there  was  proportionally  more  sulphur  deposited  by  the  neutral  Nico- 
sul  than  in  the  dilution  of  one  to  ten,  and  .87  of  one  per  cenJ  more  sulphur 
thrown  out  by  the  use  of  neutral  Nico-sul  than  with  the  acid  Nico-sul.  At  the 
dilution  of  one  to  twenty  the  results  indicate  tnat  it  is  best  to  use  neutral  or 
just  slightly  alkaline  Nicotine  compounds  and  not  the  acid  Nicotine  sol- 
ution, as  "Nico-Sul,"  with  the  dilute  Lime-sulphur  solution. 

Although  the  use  of  neutral  Nico-sul  solution  gave  a  slight  higher  result 
in  the  loss  of  sulphur  than  the  acid  Nico-sul  solution,  the  loss  of  Calcurn  wa* 
not  as  great. 


TABLE  E. 


25  cc.  of  the  concentrated  Lime-sulphur  solution  was  diluted    to    1000    cc, 
by  the  addition  of  water  after  the  following  were  added: 


Per 

lOOcc. 
of  Sol. 

Dilute 
Lime-sul- 
Solution 

Lead  Ar- 
senate 
(acid) 

2cc.  Nico- 
sul.  (acid) 
Lead  Arse- 
nate  (acid) 

2cc.  Nico- 
sul.  (neut.) 
Lead  Arse- 
nate  (neut) 

2cc.  Nico- 
fume  (alka) 
Lead  Arse- 
nate  (acid) 

Grams  of 

Total  S. 

.3703 

.3072 

.2693 

.3565 

.3468 

Grams  of 

S.  lost 

.0000 

.0636 

.1015 

.1043 

.0240 

Grams  of 

Lime 

.1836 

.1800 

.1768 

.1720 

.1772 

Grams  of 

Lime  lost 

.0000 

.0036 

.0068 

.0116 

.0064 

Grams  of 

Calcium 

.1311 

.1285 

.1263 

.1228 

.1266 

Grams  of 

Ca.  lost 

.0000 

.0026 

.0048 

.0083 

.0045 

Percent. 

loss  of 

Total  S. 

.0000 

17.15 

27.37 

3.08 

6.47 

Percent. 

loss  of 

Calcium. 

.0000 

1.98 

0.36 

6.32 

3.43 

The  results  in  Experiment  No.  5,  as  found  in  Table  E.  shows  that  at  the 
dilution  of  one  to  forty  the  largest  loss  of  sulphur  was  when  the  2  cc.  of  acid 
Nico-sul  and  the  acid  Lead  Arsenate  were  used  together  giving  a  loss  of  27.37 
percent  of  sulphur  and  a  loss  of  only  .36  of  one  percent  of  Calcium.  The  acid 
Lead  Arsenate  gave  a  loss  of  17.15  percent  of  sulphur  and  1.98  percent  of 
Calcium,  showing  that  the  Lead  Arsenate  mixed  with  2  cc.  of  acid  Nico-sul 
has  a  stronger  reaction  on  a  solution  of  Lime-sulphur  diluted  one  to  forty  than 
on  a  dilution  of  one  to  twenty  than  the  Lead  Arsenate  alone,  this  alto  shows 
that  an  acid  solution  of  Nicosul  throws  out  of  solution  more  sulphur  from  a  so- 
lution of  one  to  forty  dilution  than  a  one  to  twenty  dilution  as  also  indicated 
in  Experiment  three,  where  the  dilute  Lime-sulphur  was  treated  alone  with 
2  cc.  of  acid  Nico-sul.  The  amount  of  Calcium  lost  is  very  small  in  all  of  the 
mixtures,  showing  that  an  excess  of  alkali  has  a  tendency  to  throw  it  out 
of  solution  as  shown  when  alkaline  Nico-fume  is  used. 

At  the  dilution  of  one  to  forty  the  results  indicate  that  it  is  best  to  use  as 
near  neutral  solution  of  Nicotine  compound  that  is  obtainable  and  a  neutral 
Lead  Arsenate  when  mixing  them  with  a  dilute  Lime-sulphur  solution. 

Experiment  No.  6,  was  to  determine  the  amount  of  Sulphur  and  Calcium 
lost  from  the  Lime-sulphur  solution  by  the  addition  of  exactly  neutral  or 
slightly  alkaline  Lead  Arsenate  at  the  rate  of  four  pounds  to  100  gallons  of  the 
solution  containing  2  cc.  of  neutral  or  slightly  alkaline  Nicotine  compound. 
Dilution  of  the  Lime-sulphur  solution  was  one  to  forty. 


TABLE  F. 

25  cc.  of  the  concentrated  Lime-sulphur  solution  was  diluted  tn    1000    cc. 
by  the  addition  of  water  after  the  following  were  added:- 


Per 
100  cc. 
of  Sol. 

Dilute 
Lime-sul. 
Solution 

Exactly 
Neutral 
Lead  Ar- 
senate 

Exactly 
Neutral 
Lead  Ar- 
senate 
Nico-fume 

Slightly 
Alkaline 
Lead  Ar- 
senate 
Nico-sul 

Slightly 
Alkaline 
Lead  Ar- 
senate 
Nico-fume 

Grams  of 

Total  S. 

.3708 

.3656 

.3648 

.3468 

.3432 

Grams  of 

S.  lost 

.0000 

.0052 

.0060 

.0240 

.0276 

Grams  of 

Lime 

.1836 

.1824 

.1755 

.1504 

.1504 

Grams  of 

Lime  lost 

.0000 

.0012 

.0080 

.0332 

.0332 

Grams  of 

Calcium 

.1311 

.1303 

.1254 

.1074 

.1074 

Grams  of 

Ca.  lost 

.0000 

.0008 

.0057 

.0237 

.0237 

Percent. 

loss  of 

Sulphur 

.0000 

1.40 

1.62 

6.47 

7.44 

Percent. 

loss  of 

Calcium 

.0000 

0.65 

5.41 

18.08 

18.08 

The  results  in  Experiment  No.  6,  as  found  in  Table  F.  shows  that  at  the 
dilution  of  one  to  forty  the  largest  loss  of  sulphur  was  when  the  slightly  al- 
kaline Lead  Arsenate  and  the  alkaline  Nico-fume  were  used;  and  when  the 
slightly  alkaline  Lead  Arsenale  and  Nico-sul  solution  were  used,  showing  that  it  is 
just  as  bad  to  have  an  alkaline  solution  as  an  acid  solution,  because  the  alkaline 
replaces  the  lime  due  to  it  being  stronger  base,  and  the  lime  forms  the  sedi- 
ment with  some  of  the  sulphur  that  was  combined  with  the  Calcium  forming 
the  Calcium  pentasulphide  (CaS5  )  which  is  very  unstable.  As  the  other  re- 
sults show,  to  have  the  best  results  a  neutral  solution  of  a  Nicotine  compound 
and  an  exactly  neutral  Lead  Arsenate  should  be  used  with  the  dilute  Lime- 
sulphur  solution  for  the  control  of  the  San  Jose  scale,  Red  Bugs,  etc.  with  one 
spraying.  There  may  be  some  slight  variations  in  results  but  the  most  of  them 
support  this  conclusion. 

In  some  evperimental  work  performed  by  Mr.  Wallace  of  the  Department 
of  Plant  Pathology,  it  was  observed  that  some  lime-sulphur  solutions  diluted 
one  to  thirty  and  saturated  with  carbon  dioxide  before  being  applied  to  the 
trees  was  effective  for  certain  troubles  and  caused  no  leaf  injury.  When,  how- 
ever, there  was  added  to  the  Lime-sulphur  solution  lead  arsenate,  at  the  rate 
of  four  pounds  to  one  hundred  gallons,  there  ivas  caused  some  black  precipi- 
tate, and  the  mixture  then  precipitated  with  carbon  dioxide  there  was  consid- 
erable leaf  injury.  Some  trees  were  nearly  completely  defoliated.  The  lead 
arsenate  of  the  same  brand  as  used  above,  when  sprayed  alone  with  water 
caused  slight  injury.  Lead  arsenate  mixed  with  Lime-sulphur  solution  as 
above,  but  without  any  connection  of  carbon  dioxide  showed  a  slight  injury, 
but  only  after  a  period  of  about  one  month. 


The  investigation  of  the  problem  as  given  was  taken  up  with  the  following 
conclusins:- 

The  injury  caused  by  the  Lead  Arsenate  alone,  when  srayed,  was  due  to 
the  soluble  arsenic,  (As2  C>5  )  which  was  .36  of  one  percent  and  it  can  be  in- 
creased by  passing  Carbon-dioxide  into  the  solution. 

When  Lime-sulphur  solution  is  treated  with  Lead  Arsenate  some  Lead 
•ulphide  is  formed,  the  black  precipitate,  and  Calcium  arsenate  set- 
ting free  some  sulphur  and  hydrogen  sulphide.  The  retarded  injury  caused 
by  the  mixing  of  lead  arsenate  with  lime-sulphur  wash  was  due  to  the  calcium 
of  the  lime  sulphur  uniting  with  some  of  the  soluble  arsenic  of  the  Lead  Ar- 
senate when  they  were  mixed.  Then  by  the  action  of  the  carbon  dioxide  of 
tke  air  upon  the  calcium  in  combination,  the  arsenic  (As2  Os  )  was  made  sol- 
uble after  a  period  of  almost  a  month. 

The  Lime-sulphur  solution  when  saturated  with  carbon-dioxide  and  then 
sprayed  gives  no  injury,  but  when  the  lime-sulphur  solution  is  first  treated 
with  lead-arsenate  then  saturated  with  carbon  dioxide,  it  gives  considerable 
leaf  injury  caused  by  the  action  of  the  carbon-dioxide  on  the  lime-sulphur  so- 
lution forming  calcium  carbonate  and  some  hydrogen  sulphide.  The  hydrogen 
sulphide  reacts  with  the  lead  arsenate  forming  lead  sulphide  (the  black  preci- 
pitate) and  some  soluble  arsenic,  which  does  the  injury.  Lead  Sulphide  is 
precipitated  from  water  containing  Lead  Arsenate  by  passing  hydrogen  sul- 
phide into  it,  although  lead  arsenate  is  insoluble  in  water. 

Lead  arsenate  used  had  .36  of  one  per  cent  of  soluble  Arsenic  (As2  Os  ), 
when  dissolved  in  distilled  water;  but  when  treated  with  water,  which  had 
been  saturated  with  Carbon-dioxide,  it  had  .44  of  one  percent  of  soluble  ar- 
senic (As2  O5  )  showing  that  water  containing  carbon-dioxide,  as  hard  waters, 
have  a  greater  dissolving  power  on  Lead  Arsenate.  Therefore  in  making  up 
spraying  solutions  should  use  as  soft  a  water  as  obtainable.  The  Lead  Arsen- 
ate and  Lime-sulphur  solution  after  being  saturated  with  carbon-dioxide  has 
.66  of  one  per  cent  of  soluble  arsenic  (As2  Os  )  showing  that  the  carbon- 
dioxide  pressure  sprayers  cannot  be  used  with  a  mixture  of  Lime-sulphur  and 
lead  arsenate,  although  it  can  be  used  to  advantage  with  the  Lime-sulphur 
solution  alone  as  the  decomposition  is  very  small  and  the  free  sulphur  being 
in  such  a  fine  condition  would  act  as  a  fungicide  which  fact  has  been 
demonstrated.  Some  soluble  arsenic  may  also  be  produced  by  the  action  of 
the  carbon-dioxide  on  the  calcium  arsenate  formed  by  the  action  of  Lime-sul- 
phur solution  on  the  lead  arsenate.  The  soluble  arsenic  is  the  damaging  pro- 
duct to  the  foliage  so  it  is  advisable  to  have  the  arsenic  in  as  insoluble  form  as 
possible.  It  is  advisable,  to  avoid  injury  to  foliage,  in  the  use  of  any  arsenical 
spraying  material,  that  may  contain  some  free  or  soluble  arsenic,  to  use  some 
milk  of  lime  in  excess,  that  is  Calcium  hydroxide  solution,  so  as  to  take  care  of 
any  soluble  arsenic  present.  This  can  also  be  used  with  the  mixture  of  Lime- 
sulphur  and  lead  arsenate,  especially  when  the  Lead  arsenate,  which  is  to  be 
mixed  with  the  dilute  Lime-sulphur  solution,  is  slightly  acid.  This  treatment 
of  the  Lead  Arsenate  before  mixing  with  the  dilute  Lime-sulphur  solution 
would  certainly  be  advisable,  especially  as  a  preventative  of  injury  to  foliage. 


/ 


SUMMARY 

1.  There  is  no  reaction  between  dilute    Lime-sulphur    solution    and    dilute 
Nicotine  solution. 

2.  In  the  use  of  Nicotine  compounds  with  dilute  Lime-sulphur  solution,  the 
best  dilution  of  Lime-sulphur  solution  to  use  is  one  to  forty. 

3.  The  use  of    acid  Nicotine  Compounds,  as    "Nico-sul"    is    not    advisable 
with  dilute  Lime-sulphur  solution,  because  a  sediment  is  produced  composed 
mostly  of  free  sulphur,  which  decreases  its  value  as  an  insecticide  or  fungicide 
to  that  amount. 

4.  If  a  too  alkaline  Nicotine  Compound  is  used  a  sediment  composed  prin- 
cipally of  Lime  (CaO)  and  a  small  amount  of  free  sulphur  is  produced. 

5.  To  obtain  the  best  results  it  is  advisable  to  use  an  exactly  neutral    or    as 
near  neutral  Nicotine  Compound  as  is  obtainable;  such    as  "Nico-fume",    with 
dilute  Lime-sulphur  solutions.  In  which  case  only  a  trace  of  sediment  is  formed. 

6.  Acid  Lead  Arsenate  cannot  be  used  with  dilute  Lime-sulphur  solutions. 

7.  Neutral  Lead  Arsenate  is  the  best  to  use  with    dilute    Lime-sulphur   so- 
lution,  and  also  to  use  with  dilute  Lime-sulphur  and  Nicotine  Compounds  for 
the  control  of  San  Jose  scale,  Red  Bugs,  etc,  with  one  spraying. 

8.  As  soft  a  water,  as  is  obtainable,  should  be  used  in  making  up  Lead  Ar- 
senate for  spraying  because  waters  high  in  dissolved  salts,  or  in  carbon  dioxide, 
makes  proportionally  more  arsenic  (As2  O$  )  soluble. 

9.  Carbon  Dioxide  pressure  sprayers  cannot  be  used  in  the  spraying  of  Lead 
Arsenate,  or  when  Lead  Arsenate  and  dilute  Lime-sulphur  solution  are  mixed, 
as  more  soluble  arsenic  (As2  Os  )  is  dissolved. 

10.  To  avoid  soluble  Arsenic  in  Lead  Arsenate  and  to  neutralize  the  acidity 
of  the  Lead  Arsenate  in  its  use  with  the  Lime-sulphur  solution,  use  an  excess 
of  milk  of  Lime  with  the  mixture.     It  can  also  be  used  to  neutralize  the   acid- 
ity  of  Nicotine  Compounds. 

1 1 .  Carbon  Dioxide  pressure  sprayers  can  be    used    safely   with    the    dilute 
Nicotine  preparations. 


GENERAL  LIBRARY 
UNIVERSITY  OF  CALIFORNIA— BERKELEY 

RETURN  TO  DESK  FROM  WHICH  BORROWED 

This  book  is  due  on  the  last  date  stamped  below,  or  on  the 

date  to  which  renewed. 
Renewed  books  are  subject  to  immediate  recall. 


ENTOMOLOGY  LIBRARY 


LD  21-100m-l,'54(1887sl6)476 


Gaylord  Bros. 

Makers 
Syracuse,  N.  Y. 

PAT.  JAN.  21,  1908 


